1. Field of the Invention
The present invention relates to a light emitting device and a light receiving device, which is used for an optical sensor and the like, employing a semiconductor element. More particularly, the present invention relates to a thin-type light emitting device used for a backlight of a liquid crystal display and the like.
2. Background Information
Semiconductor light emitting devices of high luminance and high optical output have been developed and utilized in various fields. Making use of its advantage, such as small size, low electrical consumption, and light weight, such light emitting devices have been used as, for example, a light source of a cellular phone and a backlight of a liquid crystal display, a light source of various meters, various read sensors, signaling devices, illuminations, or the like. As one of the light emitting devices used for such purposes, a thin-type light emitting device having a light emitting element disposed in a flat resin package has been known. In such light emitting devices, a lead terminal protruding from the bottom surface of the package is bent along the bottom surface of the package, and is further bent along a side surface of the package.
However, in the light emitting devices described in Japanese Laid Open Patent Publication No. 2003-168824 and Japanese Laid Open Patent Publication No. 2006-19313, the lead terminal to be soldered to a mounting substrate and the like and is capable of forming a fillet (hereinafter referred to as a fillet terminal) is only provided at each of a pair of side surfaces, and consequently, heat can be removed substantially only from the mounting surface of the soldered fillet terminals, resulting in insufficient heat dissipation.
When such a light emitting device is incorporated into an optical member such as an optical waveguide and the like, a resin portion of the back surface of the package is pressed by means of an elastic member so that the opening side of the package is closely adhered to the optical waveguide. Insufficient dimensional accuracy of the package may lead the resin incorporated therein being distorted, resulting in the semiconductor device being operated under stress, so that the reliability may be reduced due to consequent vibration or the like.